No likely but it is possible that the aortic size is relatively normal for a normal height person ( 5'10" or so). How tall is he? If he is already at this height level then this may be at the upper normal range, but if he is small and/or the aorta continues to grow significantly during puberty, then he may need surgery once the diameter reaches 5 cm, or 4.5 if he has Marfan's.
I am in the same boat as you right now.My son had his VSD repaired at age 4 yrs. 11 months old and when he had his surgery all other aspects of his heart were normal.This past May Eric went in for his 2 yr. f/u(at age almost 10) and the echo showed his aortic root is now dilated.We go back in Novmember for a 6 months f/u echo and see if Eric needs to go on B/P meds or if we can hold off a bit longer.
We went back to Eric's geneticist(he has been followed by genetics since he was 1 y.o.) to be tested for Lowey-Dietz Syndrome,which is a fairly new syndrome(about 5+ yrs. old) that was discovered that some people have that show some signs of Marfan's but not really.His cardiologist needed to know(as well as we did) as if he had Lowey-Dietz the repair would have to moved up as the anuersyms tend to rupture earlier in these patients.
I see they r/o Marfan's did they consider Lowey-Dietz since you say he is near the Marfan's spectrum..
If you even want to talk more hit me up on my profile here.
Docs on here will continue to tell you about surgery and beta blockers, but will not (for some unknown reason that I'd love to hear) tell you about the latest developments in treating people on the Marfan/Loeys Dietz spectrum.
I really get tired of typing this information out over and over, so I just tell people to click on my screen name and look at some older posts about angiotensin receptor blockers (ARBs) and ACE inhibitors. These drugs, taken in sufficiently high dosages for body size, have been shown to stop or reverse aortic dilatation in many people on the Marfan spectrum. If, after reading my old posts, you would like some corroboration, simply Google the terms "losartan" and "Marfan" and read.
Do your homework, print out the studies, and insist that your cardiologist consider them for your kids. You are their only advocate. They don't need to go undergo major surgery when a simple pill can do the trick.
I can be reached via my inbox on here if you want more information.
PS - as you may know, actually being diagnosed with "Marfan" is a side issue. The mere fact that one has a handful of connective tissue disease characteristics and a dilated root is enough to warrant proactive measures and regular monitoring.